Recent Research Advances in the Risk Assessment Method of an Underground Pressure Pipeline

This paper reviews the risk assessment method of an underground pressure pipeline, introduces the risk assessment method of expert grading, fuzzy integrative assessment, probabilistic risk assessment and extenics assessment in an underground pressure pipeline. Moreover, it puts forward the developing orientation of risk assessment.

Development and Application of Oil-Spill Risk Assessment Model for Offshore Pipeline

To the potential oil-spill risk caused by offshore pipeline more attention has been paid after the Dalian oil spill incident from oil-pipeline explosion. Since then an issue about how to prevent and control the sudden oil-spill from the offshore pipeline has been raised. In this paper, we proposed an optimized model to analyze the main causes(probability) of spill and the consequence with the fuzzy comprehensive assessment model. Considering the complicated assessment process for oil-spill, the assessment factor system involving the spill probability and consequence was established based on the operative manual and statistic leakage/damage data of offshore pipeline in order to estimate the integrated spill risk score automatically. The evaluated factors of spill probability could be grouped into five aspects: corrosion, fatigue, national damage, third party, and operational fault; the consequence evaluated factors of spill included hazard of oil and impact-controlling capability. With some modifications based on experts' opinions, each of the evaluated factors in our work was developed with a relative weight and evaluation criterion. A test example for an offshore pipeline in the Bohai waters was described to show how the model can be used for an actual case in more detail. By using the oil-spill risk assessment model, it is easy to determine the risk level associated with the ongoing activity and management level and hence to take the risk mitigation action immediately.

Quantitative risk assessment & leak detection criteria for a subsea oil export pipeline

A quantitative risk assessment （QRA） based on leak detection criteria （LDC） for the design of a proposed subsea oil export pipeline is presented in this paper. The objective of this QRA/LDC study was to determine if current leak detection methodologies were sufficient, based on QRA results, while excluding the use of statistical leak detection; if not, an appropriate LDC for the leak detection system would need to be established. The famous UK PARLOC database was used for the calculation of pipeline failure rates, and the software POSVCM from MMS was used for oil spill simulations. QRA results revealed that the installation of a statistically based leak detection system （LDS） can significantly reduce time to leak detection, thereby mitigating the consequences of leakage. A sound LDC has been defined based on QRA study results and comments from various LDS vendors to assist the emergency response team （ERT） to quickly identify and locate leakage and employ the most effective measures to contain damage.

Oil Spill Risk Assessment of Offshore Pipeline in the Bohai Sea Under the Perspective of Ecological Protection

In recent decades,the exploration and development of marine oil and gas resources have increased significantly to meet the increasing energy demand of mankind.The Bohai Sea is a semi-closed continental sea that has a weak water exchange capacity and high ecological fragility.However,at present,more than 200 oil platforms have been built in the Bohai Sea,with more than 270 offshore oil pipelines having a length exceeding 1600 km.The oil spill pollution of offshore platforms has a great impact on the marine environment and ecosystems.Therefore,a comprehensive assessment of its risks is of great practical significance.This paper systematically constructs a comprehensive oil spill risk assessment model that combines the oil spill risk probability model and the ocean hydrodynamic model.This paper uses the Bohai Sea offshore pipeline as an example to assess its oil spill risk.The high-risk-value areas of the Bohai Sea offshore pipeline are mainly distributed at the bottom of Liaodong Bay,the bottom of Bohai Bay,near the Caofeidian area,and the northern part of the Yellow River Estuary.

THE RISK ASSESSMENT OF THE LONG-DISTANCE OILPIPELINE ENGINEERING

The oilfield construction and long-distance oil pipeline engineering has been developed extensively in China. The risk assessment of oil industry will, however, be an important objective to cope with the development of oil industry , The risk assessment of oil industry has many subjects worthy to be studied.The major purpose of the paper is to research the risk cases of long-distance oil pipeline engineering in Ganshu and Shaanxi provinces.

Research status of corrosion environment failure and safety assessment of pipeline welded joint

Pipeline transportation is an economical, safe, and efficient transportation method for transporting oil, natural gas, mineral slurry, and other fluids.Welding is the most critical construction process in pipeline engineering and is crucial in the safe operation and service of an entire pipeline system.Theoretically, the girth welded joint is the weakest link in a pipeline system.The unevenness of the structure and performance of the joint caused by welding frequently results in the failure of the welded joint before the failure of the base material of the pipe body, causing the pipeline to leak or even break.For steel pipes used in an acidic corrosive medium environment, the integration of the corrosive medium and mechanical load will accelerate the failure of the welded joint.This article reviews the failure modes of pipeline welded joints in acidic corrosive media, including stress corrosion cracking, hydrogen-induced cracking, and corrosion fracture, and corrosion fatigue considering the diffusion and accumulation of H;at the crack tip.It also reviews service pipelines in acidic corrosive media.The general processing technology of pipe joint engineering critical assessment(ECA) is investigated to provide a reference for the future development of technology in this field.

Applying Indexing Method to Gas Pipeline Risk Assessment by Using GIS: A Case Study in Savadkooh, North of Iran

Gas pipelines are environmentally sensitive because they cross varied fields, rivers, forests, populated areas, desert, hills and offshore and also different parameters in gas transmission progresses are effective. Underground gas transmission pipelines have been grown as one of the low risk methods with low cost in the world specially in middle east and Europe. Physical and chemical properties of liquid gas, pipeline properties and also its environmental condition are the main factors of increasing the technical and environmental risk. In this article the quantitative risk assessment has been done by using GIS and overlaying the information layers. For this purpose, all effective risk factors were identified and projected. In order to achieve the same and comparable results, the entire pipeline route was divided into 500 meter intervals and the risk was calculated in each interval, finally the scores of these intervals such as each criterion risk was calculated. The case study of the article is Savadkooh to PoleSefid pipeline in Mazandaran.

Risk analysis and maintenance decision making of natural gas pipelines with external corrosion based on Bayesian network

Buried natural gas pipelines are vulnerable to external corrosion because they are encased in a soil environment for a long time.Identifying the causes of external corrosion and taking specific maintenance measures is essential.In this work,a risk analysis and maintenance decision-making model for natural gas pipelines with external corrosion is proposed based on a Bayesian network.A fault tree model is first employed to identify the causes of external corrosion.The Bayesian network for risk analysis is determined accordingly.The maintenance strategies are then inserted into the Bayesian network to show a reduction of the risk.The costs of maintenance strategies and the reduced risk after maintenance are combined in an optimization function to build a decision-making model.Because of the limitations of historical data,some of the parameters in the Bayesian network are obtained from a probabilistic estimation model,which combines expert experience and fuzzy set theory.Finally,a case study is carried out to verify the feasibility of the maintenance decision model.This indicates that the method proposed in this work can be used to provide effective maintenance schemes for different pipeline external corrosion scenarios and to reduce the possible losses caused by external corrosion.

A reliability-oriented genetic algorithm-levenberg marquardt model for leak risk assessment based on time-frequency features

Since leaks in high-pressure pipelines transporting crude oil can cause severe economic losses,a reliable leak risk assessment can assist in developing an effective pipeline maintenance plan and avoiding unexpected incidents.The fast and accurate leak detection methods are essential for maintaining pipeline safety in pipeline reliability engineering.Current oil pipeline leakage signals are insufficient for feature extraction,while the training time for traditional leakage prediction models is too long.A new leak detection method is proposed based on time-frequency features and the Genetic Algorithm-Levenberg Marquardt(GA-LM)classification model for predicting the leakage status of oil pipelines.The signal that has been processed is transformed to the time and frequency domain,allowing full expression of the original signal.The traditional Back Propagation(BP)neural network is optimized by the Genetic Algorithm(GA)and Levenberg Marquardt(LM)algorithms.The results show that the recognition effect of a combined feature parameter is superior to that of a single feature parameter.The Accuracy,Precision,Recall,and F1score of the GA-LM model is 95%,93.5%,96.7%,and 95.1%,respectively,which proves that the GA-LM model has a good predictive effect and excellent stability for positive and negative samples.The proposed GA-LM model can obviously reduce training time and improve recognition efficiency.In addition,considering that a large number of samples are required for model training,a wavelet threshold method is proposed to generate sample data with higher reliability.The research results can provide an effective theoretical and technical reference for the leakage risk assessment of the actual oil pipelines.

Informational uncertainties of risk assessment about accidents of chemicals

An analysis system of informational uncertainties for accidental risk assessment of chemicals is introduced. Statistical test methods and fuzzy sets method can do the quantitative analysis of the input parameters. The uncerainties of the model can be used by quantitative compared method for the leakage accidents of chemicals. The estimation of the leaking time is important for discussing accidental source term. The uncertain analyses of the release accident for pipeline gas (CO) liquid chlorine and liquid propane gas (LPG) have been discussed.

Modeling of the mechano-electrochemical effect at corrosion defect with varied inclinations on oil/gas pipelines

A 3-dimensional finite element model was built to determine the effect of inclination angle of a corro sion defect on local mechano-electrochemical(M-E)effect in a simulated soil solution.Because of the high effect of the defect inclination angle on the M-E effect,when the inclination angle is 0°(i.e.,the primary axis of the defect parallel to the longitudinal direction of the pipe),the greate st stress concentration level at the defect can be observed,which is associated with the lowest corrosion potential,the greatest anodic current density and the most serious accelerated localized corrosion.When the inclination angle is 90°,the stress concentration level reduces and the corrosion potential becomes less negative,accompanying with the decreased anodic/cathodic current densities.Besides,when the ratio(r_(ca))of the primary axial length of the defect to its secondary axial length is 1,the defect inclination does not affect the stress and the electrochemical corrosion rate at the defect.With the increase of r_(ca),the effect of the defect inclination angle is more apparent.

Risk assessment of oil and gas pipelines hot work based on AHP-FCE

A new quantitative risk assessment method for hot work is proposed based on the analytic hierarchy process(AHP)and fuzzy comprehensive evaluation(FCE).It can help pipeline companies realize the risk management of hot work and further ensure the safe operation of oil and gas pipelines.Taking one natural gas pipeline in China as an example,this paper evaluates the risk of a single hot work in the spring of one natural gas pipeline in a high consequence region.First of all,the risk factors are determined with reference to the job safety analysis(JSA),and then experts were invited to fill out a questionnaire to collect their opinions.According to the results of the questionnaire,AHP is used to calculate the weight coefficients of the evaluation indicators,and FCE is used to evaluate the risk level of hot work.After calculation,the comprehensive risk score of hot work is 40.888.It belongs to a"general risk".This method can not only quantitatively evaluate the risk levels of hot work,but also reasonably sort the importance of various risk factors.It is helpful for the effective management of hot work and provides suggestions for implementing control measures.

Reliability-based research for failure risks of ship hull girder

In order to find a simple and programmed method to analyze the reliability of hull beams when fatigue and corrosion act on ships, the stress of ships is to be calculated in compliance with the longitudinal bending and cross-section modulus of ship beams. The calculation value of stress is to be compared with the allowable stress in order to gain the actual ship load and margin of safety, and then assess the reliability and failure probability of ship beams. The longitudinal bending moment is a random variable; the fatigue and cauterization are also random variables; and as the ship is influenced by cumulative damage of fatigue and cauterization, the cross-section modulus is a time-varying random variable. The reliability and failure probabilities can be actually reflected through the reliability analysis method. The analysis results indicate that in the service time of ships, as the age of ship increases and the fatigue and corrosion effects accumulate, the reliability of ship beams decreases and the failure probability increases, especially after 15 to 20 years.

无阴极保护燃气管道腐蚀危害的表征参量及规律

对某燃气公司2016~2020年间泄漏燃气管道的管地电位分布情况进行了统计分析,同时开展了现场腐蚀检查片埋设试验,获得了检查片腐蚀速率数据及对应的检查片通电电位、电流密度、通断电电位差、环境电阻率、地表电位梯度等5个参量,通过数据分析得出各参量与腐蚀速率的相关性及相关规律。结果表明,电流密度与管道腐蚀速率的相关性最好,皮尔逊系数高达0.95,在没有检查片的条件下,可以采用管地电位指标对管道的腐蚀风险进行评判。

含H_(2)S天然气管道内腐蚀直接评价方法的改进

为了确定H_(2)S对天然气管道内腐蚀的影响,对NACE SP0110-2010标准提出的天然气管道内腐蚀直接评价方法(包括预评价、间接评价、直接评价、后评价四个环节)进行改进,即在该方法的间接评价环节引入了CO_(2)-H_(2)S腐蚀速率预测模型和积水概率参数,提高了推荐开挖点管道腐蚀程度的准确性。并以某含H_(2)S天然气管道为例,对改进后的评价方法进行了演示。结果表明:根据间接评价(多相流腐蚀模拟计算),极严重腐蚀出现在管道前500 m处,23%管段的积水概率为1;根据直接评价(现场开挖),5个开挖点处管道均属于极严重腐蚀,最大腐蚀速率为0.337 mm/a,与间接评价的预测结果一致;根据后评价确定了管道再评估时间间隔为1 a。改进后评价方法对预测多相流含H2S天然气管道内腐蚀高危点具有一定的借鉴意义。

基于层次分析熵权组合法-云模型的充填管道堵塞风险评估

为确定充填管道堵塞的主要影响因素,采用层次分析法、熵权法和云模型理论,进行充填管道堵塞风险评估.选取充填料浆体积分数、充填倍线等12项指标,用层次分析熵权组合法得到各指标的综合权重系数后与云模型方法耦合,得到综合确定度,以判定充填管道堵塞的风险等级.依据现场资料和数据,对3处采用充填采矿法的矿山进行评估.结果表明,贡北金矿、新城金矿和开阳磷矿的充填管道堵塞风险等级分别为Ⅱ、Ⅲ、Ⅱ级,与其他方法进行对比,证明该方法精确度较高.

基于多源数据的城市社区燃气管道突发事件风险分析

随着社区燃气管道的大量铺设,燃气管网安全性问题日益突出,一旦燃气管道遭到破坏或泄漏,不仅会对人民群众的生命及财产安全造成严重的威胁,也会给城市的应急资源布局带来考验。为了探析城市社区燃气管道突发事件风险的空间特征并提出城市应急资源优化方案,首先,基于北京市POI数据,在ArcGIS软件中基于频数密度算法划分城市功能区,得出北京市功能区的分布图;然后,基于POI数据和NPP/VIIRS数据,选用SAVEE模型分别进行风险分析,再使用迭加模型,在赋予两类数据权重的前提下,汇总成基于多源数据的北京市社区燃气管道突发事件风险综合评价图;最后,基于区位-配置模型的3个不同维度提出优化方案并汇总。结果表明:短期内新建19个消防站较为合理,可将住宅小区覆盖率提高至98.76%,长期内新建24个消防站较为合理,可将住宅小区覆盖率提高至99.84%。

既有供热管网健康评估方法及案例分析

本研究基于对直埋热力管道环境风险以及自身风险分析,综合环境评估、宏观检查、防腐层检测、杂散电流检测、腐蚀环境评估,建立了一种既有供热管网健康评估方法。以天津市某一次管网供回水管道为案例进行了管网健康评估,指出了该管网健康程度提升方向。该方法将对城镇供热管线泄漏检测提供关键技术支撑,有利于提升整个供热系统运行质量。

铜合金海水管路腐蚀防护及检测技术研究现状

介绍了铜及铜合金海水管路腐蚀的研究进展,并指出铜合金海水管路的腐蚀特征,进而分析适用于海水管路的腐蚀防护技术,并介绍海水管路腐蚀检测与评估的方法,为海水管路的腐蚀防护提供参考。

加拿大某酸性气田管道完整性体系建设与实践

管道完整性管理是一种基于风险评估与控制的系统性安全管理方法。通过实施管道完整性管理,可以将风险控制在合理、可接受的范围内,预防和减少管道事故的发生。中国石化加拿大公司针对当地运营的某酸性气田集输管道的实际生产运行状况,依据加拿大通用的油气管道管理标准,按照系统完整性管理的理念,建立和完善了酸性气田管道完整性管理的技术和管理体系,通过有效实施,提高了该气田管道完整性水平,确保了管道安全高效运行。